The present invention relates to a solid-state imaging (or pickup) device which can provide an output picture or image having an excellent uniformity. The present invention also relates to a solid-state imaging device which contains a multiplicity of pixels and has an amplifying means in each pixel or plural pixels (hereinafter referred to as pixel amplifier). The present invention further relates to a solid-state imaging device in which high-speed signal read-out can be successfully made.
Solid-state imaging devices on the market include an MOS solid-state imaging device and a CCD imaging device. On the other hand, in order to improve the sensitivity and the dynamic range, a solid-state imaging device having an amplifying means in each pixel is now under study and development (see Ando et al, "TRIAL MANUFACTURE OF AMPLIFYING TYPE OF MOS AREA SENSOR (GCMA)", Proceedings of the Institute of Electronics and communication Engineers of Japan, 1241, 1983). The solid-state imaging device having an amplifying means in each pixel is characterized in that each of photoelectric conversion elements or photodiodes on a face plate is provided with an amplifying means adjacent thereto for amplifying electric (or signal) charges produced in the photoelectric conversion element.
The above-mentioned conventional solid-state imaging device having an amplifying means in each pixel will now be explained by virtue of FIG. 1 which shows the construction thereof.
In FIG. 1, reference numeral 1 designates photoelectric conversion elements or photodiodes, numeral 2 amplifier transistors in pixels, numeral 3 selective transistors, numeral 4 reset transistors, numeral 5 power supply lines, numeral 6 vertical scanning lines, numeral 7 vertical signal lines, numeral 8 horizontal switching transistors, numeral 9 an output line, symbol YDC a Y driver circuit or vertical shift register, and symbol XDC an X driver circuit or horizontal shift register. The photoelectric conversion element 1 is connected to the gate of the pixel amplifier transistor 2 which has a signal amplifying function. The source of the pixel amplifier transistor 2 is connected to the vertical signal line 7 and the drain thereof is connected to the source of the selective transistor 3 which operates to select the pixel amplifier transistor 2. One pixel is formed by the photoelectric conversion element 1, the pixel amplifier transistor 2, the selective transistor 3 and the reset transistor 4. The photoelectric conversion elements 1, the pixel amplifier transistors 2 and the power supply lines 5 are formed on a face plate. The area sensor reported by the above-mentioned Ando et al's article includes 136 (horizontal).times.102 (vertical) elements.
The gate of the selective transistor 3 is scanned by the vertical scanning line 6 and the drain thereof is supplied with a current from the power supply line 5.
The gate of the reset transistor 4 which resets the photoelectric conversion element 1 is scanned by the vertical scanning line 6 adjacent to the vertical scanning line 6 which scans the gate of the selective transistor 3 in the pixel containing that reset transistor 4. The source and drain of the reset transistor 4 are connected to the photoelectric conversion element 1 and the power supply line 5, respectively.
Each pixel has a signal amplifying means or circuit which is formed by the pixel amplifier transistor 2, the selective transistor 3 and the reset transistor 4. These transistors are driven by the Y driver circuit YDC through the power supply line 5 and the vertical scanning line 6.
The vertical signal line 7 which transfers an amplified signal current is connected to the output line 9 through the horizontal switching transistor 8 scanned by the X driver circuit XDC. The X driver circuit XDC and the horizontal switching transistor 8 forms a transfer or read-out means for the amplified signal.
In operation, electric (or signal) charges produced by photoelectric conversion of light (or optical signal) incident upon the photoelectric conversion element 1 changes the gate voltage of the pixel amplifier transistor 2. Now provided that the power supply line 5 and the vertical scanning line 6 in the n-th row in a vertical direction are selected by the Y driver circuit YDC in a horizontal blanking period, the potentials of those selected lines take high levels so that the selective transistors 3 in the n-th row are turned on and hence the drains of the pixel amplifier transistors 2 in the n-th row take high levels. Next, if the horizontal switching transistor 8 in the m-th column is turned on through the scan thereof by the X driver circuit XDC in a horizontal scanning period, the vertical signal line 7 in the m-th column in a horizontal direction is coupled to the output line 9 through the horizontal switching transistor 8. Thus, since the drain of the pixel amplifier transistor 2 in the n-th row in the vertical direction and in the m-th column in the horizontal direction takes its high level and the source thereof is coupled to the output line 9, an output current corresponding to the gate voltage of the pixel amplifier transistor 2 is supplied to the output line 9.
Amplified signal outputs can be obtained by successively operating the pixel amplifier transistors 2 in the horizontal and vertical directions as has been explained in the above. The resetting of the photoelectric conversion elements 1 in the n-th row in the vertical direction is made in such a manner that the vertical scanning line 6 in the (n+1)th row in the vertical direction is turned to a high level in the next horizontal blanking period, thereby turning off the reset transistors 4 in the n-th row in the vertical direction.